As it is known, laminated glass consists of two or more layers of glass; between them one or more layers of polyvinyl butyral (PVB) are sandwiched. Such that for laminated glass first-use polyvinyl butyral (PVB) is used as the layer in between due to its excellent features: great adherence to glass, high impact strength, high flexibility, excellent optical clarity, high stability (especially against ultraviolet rays), thermal stability or insensitivity to moisture. In turn, one must add a good thermoplastic output, which means that polyvinyl butyral (PVB) has been produced in major commercial quantities since the 1940's.
In contrast with all the aforementioned virtues, the manufacture of polyvinyl butyral (PVB) is expensive (6-9/kilo), therefore recycling is a technique which can provide this product with a high degree of added value, up to date no method have been previously developed that could produce a product pure enough to be reused as layer in laminated glass.
Therefore, the material disposed is being buried or incinerated, causing a tremendous impact on the environment as a result of the air pollution generated.
Throughout history, different unsuccessful attempts have been made to achieve polyvinyl butyral (PVB) recycling. Thus, for example, several glass recycling plants in Germany are capable of separating the glass from the polyvinyl butyral (PVB), however this polyvinyl butyral (PVB) is unfortunately not suitable for reuse due to the high content of rubber and glass fractions.
A German institute in Thüringen leaded a research study on the purification of polyvinyl butyral (PVB) from vehicle windshield glass some years ago in which different purification methods were used on pieces of raw polyvinyl butyral (PVB) contaminated with all types of impurities.
Flotation separation and different melt filtering methods resulted in a purer material, but there continued to be a large quantity of contaminating particles such as rubber and glass, causing the quality of the resulting material not to be sufficiently acceptable for its reuse in different types of applications.
The effort made up to date for the recycling of polyvinyl butyral (PVB) obtained from End of Life Vehicles (ELVs) has been tremendous, but the technologies employed have not achieved a plastic which is purified to a high enough degree.
Up to date, solely lower-quality applications such as wall tiles, acoustic insulation, asphalt mixes, etc. have been found for making good use of recycled polyvinyl butyral (PVB).
These applications must be assessed as a poor substitute for the reuse of laminated glass in terms of equivalent value. The development of additional, high-value applications for the polyvinyl butyral (PVB) recovered from laminated glass, stemming from a higher quality of the resulting product, many boost the economic feasibility of recycling this material, achieving, in turn, some major benefits at the environmental level.
The most highly advanced polyvinyl butyral (PVB) recycling processes are currently:                Dry separation process of Societá per L'Elettronica Applicata (SEA), Villanova (Bologne) Italy.        
As an alternative to the conventional methods, this process introduces a separation of the polyvinyl butyral (PVB) from glass consisting of a dry filtering in melted state based on the different physical properties of these two materials combined with an ultrasound gravitational separation method.                Flotation separation using fluid of a density >1.0 g/cm3 of Thueringisches Institut fur Kunstoff-Forschung eV (TITK), Rodulstadt, Germany.        
The current recycling methods set out by the company TITK (Rudolstadt, Germany) and based on a pilot polyvinyl butyral (PVB) and glass separation line are structured as follows:
The method starts with a first separation stage, in which techniques based on the fragility differential between these two materials are employed. By passing the windshields through three rollers, the layer of glass will be shattered and the remaining flexible plastic will remain in a whole sheet, to then be put through the flotation separation line, which is comprised the following stages:
Stage 1: A fluid with a density of 1.0 g/ml is used for eliminate the polyolefins (Polypropylene and Polyethylene), as well as the dust and grime incrusted on the surface.
Stage 2: In this second stage, the polyvinyl butyral (PVB) effluent still contaminated with glass, rubber, etc. is placed in water containing Na2SO4 (d=1.1 g/ml), thus achieving two flows:PVB+Na2SO4PVB+(PA, PET, Glass, Rubber, etc).
Stage 3: This last stage revolves round the separation of the (PVB) and Na2SO4 by way of water flotation, obtaining a more highly pure flow (PVB).
These techniques do not achieve a degree of purity high enough for the reuse thereof as polyvinyl butyral (PVB) sheets for manufacturing laminated glass, therefore being necessary to be considered other techniques.
The recent advances in separation techniques have transformed the field under study, such as, for example, the selective flocculation separation systems, being possible to develop systems which, barely ten years ago, would have been thought to be impossible for industrial-level separation.
These methods have now already been successfully applied in the separation of contaminants from silicone but up to date have never been used for eliminating the contaminants from polyvinyl butyral (PVB).
There are currently patents related to the recycling of polyvinyl butyral (PVB), being possible to mention those in following:                DE 19509244 held by BUNA SOW LEUNA OLEFINVERB GmbH, in which a method is described for the recovery of polyvinyl butyral from laminated glass preventing the physical and chemical breakdown thereof, for which the polyvinyl butyral (PVB) is melted down and the residual impurities are removed by means of separation of the two thereof and then reinserting into the process.        DE 19811199 held by VIDEO COMPUTER RECYCLING, in which a method is described for the recovery of polyvinyl butyral from safety glass and process equipment, in which the polyvinyl butyral (PVB) undergoes purification, but using autoclaves, high temperatures, inert gases, among others, such that the (PVB) is melted down, and treatments are then carried out for obtaining the pure, solid (PVB).        DE 10301738 held by VIGOR GmbH VIDEO COMP RECYCLIN, in which a method is described for recovering polyvinyl butyral from laminated safety glass which entails placing in water containing a metal alcoholate catalyst and with a free additive in water prior to the drying and granulating thereof, based on a (PVB) purification by means of an high-temperature agitation treatment with a metal alcoholate as the catalyst.        
To complete the description provided hereinbelow and for the purpose of aiding toward a better comprehension of the characteristics of this invention, a set of drawings is furnished along with this specification, in the figures of which, the most characteristic details of the invention are shown for illustrative yet non-limiting purposes.